Method of making a protected metal article



Feb. 12, 1963 K. OGANOWSKI METHOD OF MAKING A PROTECTED METAL ARTICLE Filed Oct. 27, 1958 I NVEN TOR. liirs/M/q Osman/51w,

A TTQRNEYS United States Patent Office 3,677,332 Patented Feb. 12, 1983 3,977,932 ltiE'lll'rl'GD @FE MAKENG A PROTECTED METAL ARTECLE Kasimir @ganowshi, West lifiddietown, Ghio, assignor to Armco Steel Corparation, Middletown, Qhie, a corporation of Ohio Filed Oct. 27, 1958, er. No. 76%67o 6 Qlaims. (ill. 29-47351) This invention relates to a method of making a protected metal article. In the Coffman patent, No. 1,862,- 332 there was disclosed a metal article such as a sheet or strip, coated preferably on both surfaces with tin, zinc, lead, cadmium or similar metals or alloys having a lower melting point than the steel and having pressed into the coating metal, while in a mushy state, a layer of fibrous material such as asbestos felt or the like. In that patent the invention was disclosed principally with tin coated .steel sheet and according to the teachings thereof, the

coated sheet was assembled with the felt layers and then placed in an oven to render the tin coating fluid, and, while the tin coating was in a fluid state, the felt layers were pressed into position so that when the sheet was cooled, the felt layer was adhesively bonded to the tin layer.

In a later patent of the same inventor, No. 2,073,334, a teaching was made with respect to zinc coated sheets or strips and according to the teachings of this later patent, the felt layers were fed into contact with the strip immediately after it issued from the coating pot before the coating metal had solidified.

According to a still later patent of the same inventor, No. 2,764,808, the strip issued from the bath in a substantially vertical direction and the felt layers were fed into contact with the strip while passing in a vertical direction and while the coating metal was still fluid.

Over the years, therefore, where it was desired to provide a Zinc coated strip with a protective asbestos felt layer, the practice has been to do this continuously and to apply the felt layer immediately as the strip emerges from the coating pot.

This operation has not been completely successful for the reason that it is customary during a coating operation to operate on the constant tonnage principle which involves changing the speed of travel of the steel strip as the gauge changes. However, in order to produce a proper bond with asbestos felt or the like in the process of which the coating must be subjected to the pressure of bonding rolls, it is desirable for most consistent results to operate at constant speed.

Commercial processes with zinc coated strip therefore have been a compromise of one sort or another between the ideal for a coating operation and the ideal for a bonding operation.

While the first of the above mentioned Coffman patents taught the ideas of remelting the coating, this procedure has only proved satisfactory for tin but has been completely unsatisfactory for zinc.

With the foregoing considerations in mind, it is an object of the present invention to provide a method of applying a protective asbestos felt or the like layer on a zinc coated member by the remelting of a previously applied zinc coating.

It is another object of the invention to provide means for rapidly heating a coated strip to remelt the zinc so that the felt layer may be adhesively bonded thereto and to carry out the remelting at such a high speed that no substantial alloying of the zinc with the base metal can take place whereby a commercially successful product may be achieved.

Reference is made to the drawings forming a part hereof and in which the single FIGURE is a diagrammatic view of an apparatus for carrying out the method which will now be described.

Briefly, in the practice of the invention I use a sheet or strip which has previously been zinc coated, and on which the zinc coating has solidified. I then reheat the zinc coating substantially instantaneously by induction heating or by radiant heating and immediately bring the felt material into contact with the softened zinc coating and permit the coating to solidify again. Because of the fact that the heating is so rapid that it is almost instantaneous (i.e. a matter of a few seconds), the zinc of the coating will not alloy with the base metal before an adhesive bond with the felt has been accomplished.

Referring to the drawing, a coil of zinc coated steel strip is shown in the form of a coil it? from which the strip 26 is unwound. The strip passes through a rapid heating means 3% and immediately the felt material 8%, 9t (unwound from the coils 5i), 4%) is brought into contact with the strip and pressed into the mushy coating metal by the pressure rolls as, Ill. The strip protected by the felt layers may subsequently be impregnated with liquid asphalt in well known and conventional manner (not shown).

While in the drawing the strip is shown as moving horizontally, it may of course move vertically through the re melting and fibrous bonding unit without departing from the spirit of the invention.

The instantaneous heating means may be inductive heating means formed of a single loop or a plurality of loops of wire through or between which the strip passes and which coils are supplied with electrical energy at high frequency. If the energy supplied is perhaps 10 kilowatts at a frequency of kilocycles, the strip temperature is raised to the point where the zinc coating becomes molten in a matter of a very few seconds so that the pressure rolls 6t, 7% may be placed very close to the heating means 3-1? and the felt layers thereby brought into contact with the molten coating on the strip. Alternatively, the heating means may be high gradient radiant burners or other rapid heating means.

In this way, the Zinc is only brought to the fiuid state for a very short time and is immediately permitted to resolidify, and for this reason there is insufficient time for the Zinc coating metal to alloy excessively with the base metal. The zinc coating is therefore not adversely affected by the remelting.

The Coifman teachings were satisfactory for tin coated material because tin may be molten for a few minutes without serious alloying with the steel. However, when the practice of the earliest Coffrnan patent was tried with zinc, the results were never commercially satisfactory and it is for this reason that with zinc coated steel the felt layers were always applied immediately after the steel emerged from the coating pot and before the zinc coating solidified. As pointed out above, however, this procedure was unsatisfactory because it was a compromise between ideal conditions for zinc coating and ideal conditions for bonding the felt material.

By the method taught herein, the steel may be zinc coated under ideal conditions and the zinc coating may be remelted and the felt layers applied at constant speed under ideal conditions for bonding without adversely affecting the zinc coating.

It will be clear that numerous modifications may be made without departing from the spirit of the invention and I therefore do not intend to limit myself otherwise than as set forth in the claims which follow.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. T he method of protecting with a fibrous layer a zinc coated steel member which consists in moving said member at constant speed while rapidly heating said member to rernelt said zinc coating, and immediately bringing a fibrous layer into contact with said molten Zinc coating and pressing it firmly into engagement therewith, while permitting said zinc coating to resolidify, the heating rate being sufficiently rapid to permit application of the fibrous layer to the molten zinc coating before said zinc coating can become alloyed with the steel.

2. The method of protecting with a fibrous layer a zinc coated steel strip which consists in moving said strip at a constant speed while heating said strip to rernelt said Zinc coating, and immediately bringing a fibrous layer into contact with said molten zinc coating and pressing it firmly into engagement therewith, while permitting said zinc coating to resolidify, the heating rate being sulficient- 1y rapid to permit application of the fibrous layer to the molten zinc coating before said zinc coating can become alloyed with the steel.

3. The method of producing a fibrous-layer protected zinc coated steel member, which consists of zinc coating said member on the constant tonnage principle wherein the speed of travel of the steel member changes as its gauge changes, permitting said zinc coating to solidify on said member, and thereafter moving said member at constant speed while rapidly heating said member to re melt said zinc coating and immediately bringing a fibrous layer into contact with the molten zinc coating and pressing it firmly into engagement therewith, while permitting said zinc coating to resolidify.

4. The method of producing a fibrous-layer-protected zinc coated steel strip, which consists in zinc coating said strip on the constant tonnage principle wherein the speed of travel of the strip changes as the gauge changes, permitting said zinc coating to solidify on said strip and thereafter moving said strip at constant speed while rapidly heating said strip to remelt said Zinc coating, and immediately bringing a fibrous layer into contact with said molten zinc coating and pressing it firmly into engagement therewith while permitting said zinc coating to resolidify.

5. The method of claim 3, wherein the heating of said member to rernelt said zinc coating and the bringing of the fibrous layer into contact with the molten zinc coating are accomplished in a matter of a few seconds.

6. The method according to claim vl, wherein the heating of said member to remelt said zinc coating and the bringing of the fibrous layer into contact with the molten zinc coating are accomplished in a matter of a few seconds.

References Cited in the file of this patent UNITED STATES PATENTS 1,862,332 Coifman June 7, 1932 2,073,334 Coffman Mar. 9, 1937 2,262,901 Murphy Nov. 18, 1941 2,724,177 Cofi'man et al. Nov. 22, 1955 2,764,808 Cofiman Oct. 2, 1956 2,937,436 Butler et a1. May 24, 1960 

1. THE METHOD OF PROTECTING WITH A FIBROUS LAYER A ZINC COATED STEEL MEMBER WHICH CONSISTS IN MOVING SAID MEMBER AT CONSTANT SPEED WHILE RAPIDLY HEATING SAID MEMBER TO REMELT SAID ZINC COATING, AN IMMEDIATELY BRINGING A FIBROUS LAYER INTO CONTACT WITH SAID MOLTEN ZINC COATING AND PRESSING IT FIRMLY INTO ENGAGEMENT THEREWITH, WHILE PERMITTING SAID ZINC COATING TO RESOLIDIFY, THE HEATING RATE BEING SUFFICIENTLY RAPID TO PERMIT APPLICATION OF THE FIBROUS LAYER TO THE MOLTEN ZINC COATING BEFORE SAID ZINC COATING CAN BECOME ALLOYED WITH THE STEEL.
 3. THE METHOD OF PRODUCING A FIBROUS-LAYER PROTECTED ZINC COATED STEEL MEMBER, WHICH CONSISTS OF ZINC COATING SAID MEMBER ON THE CONSTANT TONNAGE PRINCIPLE WHEREIN THE SPEED OF TRAVEL OF THE STEEL MEMBER CHANGES AS ITS GAUGE CHANGES, PERMITTING SAID ZINC COATING TO SOLIDIFY ON SAID MEMBER, AND THEREAFER MOVING SAID MEMBER AT CONSTANT SPEED WHILE RAPIDLY HEATING SAID MEMBER TO REMELT SAID ZINC COATING AND IMMEDIATELY BRINGING A FIBROUS LAYER INTO CONTACT WITH THE MOLTEN ZINC COATING AND PRESSING IT FIRMLY INTO ENGAGEMENT THEREWITH, WHILE PERMITTING SAID ZINC COATING TO RESOLIDIFY. 